1. Field of the Invention
The present invention relates to disk drives for computer systems. More particularly, the present invention relates to a disk drive employing a multi-phase rotational position optimization (RPO) algorithm.
2. Description of the Prior Art
A disk drive may employ an RPO algorithm in order to execute commands in an order which minimizes the seek latency of the head as well as the rotational latency of the disk. After executing a current command, the RPO algorithm will typically evaluate seek parameters to select the next command that minimizes the access time with respect to the radial and circumferential location of the head. However, it may be desirable for the RPO algorithm to consider other parameters in addition to seek parameters when ordering the commands in the RPO queue. For example, if the disk drive is low on cache memory the RPO algorithm may order the write commands in the RPO queue relative to their size so that larger write commands will be executed first, thereby freeing cache memory for other commands. However, increasing the number of parameters considered by the RPO algorithm increases the computational complexity and latency, thereby degrading the ability to select the next best command in real-time.